The cracks damaged your touch panel so it does not work anymore.
You have to replace the touch panel to let it work again.
But at the moment the 520 is very cheap so i do not know what is cheaper.
Send your 520 for repair or buy a new one.
And if you send it to repair be sure that they use a genuine original OEM part to replace the broken touch panel.

The cracks damaged your touch panel so it does not work anymore.
You have to replace the touch panel to let it work again.
But at the moment the 520 is very cheap so i do not know what is cheaper.
Send your 520 for repair or buy a new one.
And if you send it to repair be sure that they use a genuine original OEM part to replace the broken touch panel.